[tommyboy123x]

i need to "translate" from python to C. At least i think its Python..... I guess i don't want a complete answer because that would ruin the fun of programming . I do, however, want to know what "mod" means in Python as well as a little help here an there in this code:

limit = 1000000 // arbitrary search limit
for (n = 5; n <= limit; n++) {
  is_prime[n] = false // initialize the sieve
}

// put in candidate primes: 
// integers which have an odd number of representations by certain quadratic forms
for (x = 1; x <= sqrt (limit); x++) {
  for (y = 1; y <= sqrt (limit); y++) {
    n = 4x^2+y^2
    if n <= limit and n mod 12 == 1 or 5 then is_prime[n] = not (is_prime[n])
    n = 3x^2+y^2
    if n <= limit and n mod 12 == 7 then is_prime[n] = not (is_prime[n])
    n = 3x^2-y^2
    if x > y and n <= limit and n mod 12 == 11 then is_prime[n] = not (is_prime[n])
  }
}

// eliminate composites by sieving
for (n = 5; n <= sqrt (limit); n++) {
  if is_prime[n] then {
     // n is prime, omit multiples of its square; this is sufficient because 
     // composites which managed to get on the list cannot be square-free
     for (k = n^2; k <= limit; k += n^2) {
        is_prime[k] = false
     }
  }
}

print 2, 3
for (n = 5; n <= limit; n++) {
  if is_prime[n] then print n
}

this genereates prime numbers, and i just want to change it to C as easily as possible. So first off, what is the "mod" that is in bold above?

also, how can i make this start at, lets say, 100 instead of 5? do i just make n equal to something else?

I understand that with translating code, you will lose some effieciency and stuff, but i just want to map out how this script works and write it in C. However im sure im going to need to post here again for some help on something as well

thanks!

[tommyboy123x]

that is python...... right?

or is it something else?? (if so what is it, and still... what is the mod? )

[jaeusm]

I don't know python, but to answer your question about mod:
x mod y returns the remainder (not the quotient!) of x/y (that is, x divided by y). The modulus operator in C is the percentage sign, %.

[tommyboy123x]

ok, that makes sense.... thanks

the algorithm works by using a remainder of 60, and then if it is in "list 1" then it is not a prime number, etc.

I think i have it from here, thank you!

[furtivefelon]

eh, that's not python..

Read the about in your compiler, seems like a generic C-based language, not sure what that is exactly.

[tommyboy123x]

yeah, no, i realized that too... just a few days after posting, but i didnt bother to edit my posts

but yea, it still has to do with the remainder